Abstract: Because of its safety and high efficiency,blasting demolition technology has become the preferred technology for demolition of high-rise buildings.In recent years,urban high-rise buildings have gradually shown the characteristics of large scale,complex environment and various structures.Aiming at solving the problem of limited collapse space in the blasting demolition of buildings in complex urban environment,the basic principle of longitudinal span-by-span collapse blasting demolition technology is analyzed with several typical engineering cases of blasting demolition.Meanwhile,the design principles of related blasting parameters are discussed and summarized.The trapezoidal blasting incision should be adopted in the longitudinal span-by-span collapse mode,the closure angle of the incision should be no less than 25°,and the support area with sufficient stiffness should be reserved in the rear row.Furthermore,the extension time of longitudinal partition should be 0.3~0.6 s,and the partition delay time of frame-shear structure buildings with a large longitudinal span or stiffness should be properly extended.Through three examples of blasting demolition of buildings,the feasibility of the simulation and analysis of the longitudinal and span collapse blasting design scheme of buildings by dynamic finite element software is expounded.In simulation calculation,the failure of main components of buildings is controlled by tensile stress or principal strain failure.By a contrastive analysis,longitudinal span-by-span collapse blasting technology has the advantages of small accumulation range of blasting pile,good crushing and disintegration effect,and reduction of building touchdown vibration.It is suitable for the blasting demolition of the buildings with small height-width and large length-width ratios,and it has broad application prospects.In practical engineering,the best blasting scheme should be determined according to the comprehensive comparison of site environmental conditions,building structure characteristics and technical risks.